Platform Will Not Lower; Platform Drives Slow; Platform Will Not Drive In Forward Or Reverse; Brake(S) Will Not Release (Pin Brakes) - Skyjack SJ3220 Service Manual

Section 4 – Troubleshooting Information

4.3-6 Platform Will Not Lower

1. Defective Lift valve 3H-14.
2. Defective Holding valves 2H-13-1 and/or 2H-13-2.
(if equipped)
3. Machine overloaded and Overload Lights PL-1
and PL-2 on Emergency Stop buttons flashing.

4.3-7 Platform Drives Slow

1. Free-wheeling valve V2 open or defective.
2. Flow divider/combiner FD1 defective or is
plugged.
3. Defective Speed valves 2H-18A-1 and/or
3H-18A-2.
4. Defective Counterbalance valve CB1.
5. Drive Motors M1 and/or M2 defective.

4.3-8 Platform Will Not Drive in Forward or Reverse

1. Open Free-Wheeling valve V2.
2. Brakes are not released.
3. Forward Drive valve 4H-16 or Reverse Drive valve
4H-15 is defective.
4. Flow/Divider/Combiner valve FD1 defective or is
plugged.
5. Defective Counterbalance valve CB1.
6. Drive Motors M1 and/or M2 defective.

4.3-9 Brake(s) will not Release (Pin Brakes)

1. Brake valve 3H-17 is defective.
2. Defective or plugged Brake Orifice O6
(SJ3220/26) or Orifice O5 (SJ4720/26/32).
3. Leaking or defective Brake Cylinder.
223198ABA
118
Check valve. Replace if defective.
Clean valves. Replace if defective.
Check machine limits and reduce weight as
required. Refer to electrical troubleshooting.
Close valve. Replace if defective.
Close valve and clean if necessary. Replace if
defective.
Check valve. Replace if defective.
Check valve. Replace if defective.
Check motors. Replace if defective.
Close Valve. Replace if defective.
Check brakes. Replace if defective.
Check Valve. Replace if defective.
Check Valve. Replace if defective.
Check valve. Replace if defective.
Check motors. Replace if defective.
Check valve. Replace if defective.
Check valve. Replace if defective.
Check cylinder. Replace or repair if defective.
SJ3220, SJ3226, SJ4720, SJ4726, SJ4732
Hydraulic System